The objectives of this protocol are: 1. To obtain information concerning the biochemical processes by which oxidant air pollutants produce their deleterious effects in the lung. 2. To provide animal dose response data of use in determining appropriate community air quality standards. 3. To investigate the methodalogy required to evaluate combined exposure to two air pollutants (ozone and nitrogen dioxide) with the aim of establishing whether air quality criteria based on separate studies of individual pollutants are germane to populations breathing multiple pollutants simultaneously. BIBLIOGRAPHIC REFERENCES: Goldstein, B.D.: The combined effects of ozone and nitrogen dioxide. Environmental Health Perspectives, in press, 1977. Goldstein, B.D., Marks, C.E., and Goldring, R.M.: Red cell 2,3-diphosphoglyceric acid and methemoglobin levels in workmen occupationally exposed to automobile exhaust. International Arch. Occupational Environmental Health, In press, 1977.